Structural, electronic, magnetic and optical properties of GdCuX₂ (X = S, Se and Te) compounds

Density functional theory (DFT) was used to study the structural, electronic, magnetic, and optical properties of the rare-earth-based ternary chalcogenide GdCuX₂ (X = S, Se, and Te). DFT calculations were performed using the Tran-Blaha modified Becke-Johnson (TB-mBJ) generalized gradient approximation (GGA), generalized gradient approximation with Hubbard U (GGA + U), and spin orbit coupling (GGA + U + SOC) potentials. In structural properties, we computed the ground state energy, with equilibrium volume, and lattice parameters for GdCuS₂, GdCuSe₂, and GdCuTe₂ compounds. The structural properties show that the GdCuS₂, GdCuSe₂ and GdCuTe₂ compounds have stable structures at the Wycoff position. The electronic properties were calculated in terms of the density of states (DOS) and electronic band diagram. Electronic properties confirm the semiconductor nature of GdCuS₂, GdCuSe₂, and GdCuTe₂ compounds using TB-mBJ, GGA, and GGA + U potentials. However, the GdCuTe₂ compound displays a metallic nature when using the GGA + U + SOC potential. Magnetic properties in terms of spin polarization magnetic moments of GdCuS₂, GdCuSe₂ and GdCuTe₂ compounds. With magnetic optimisation, we made a graph of the energy vs. volume curve to show that ferromagnetic [FM] is more stable than antiferromagnetic [AFM] and nonmagnetic [NM]. The GdCuS₂, GdCuSe₂ and GdCuTe₂ compounds show a good ferromagnetic nature. The optical properties of the compounds in terms of dielectric functions, refractive indices, and absorption coefficients. In the visible and infrared ranges, the optical properties reveal an upstate semiconductor nature and a downstate metallic nature. In the higher energy range, the maximum absorption is observed in the optical properties.